Week 12WednesdayEstimating 3-Number Sums
1Warm-up: ±10 Mental Math

2-min Fluency Warm-up — Mental math.

67 − 10 =

34 + 10 =

55 − 10 =

23 + 10 =

2Estimate First!

Estimate First! Round each number to the nearest 10, add, then find the actual answer.

28 + 13 + 25

Estimate (30+10+20):

Actual:

44 + 17 + 36

Estimate (40+20+40):

Actual:

52 + 28 + 19

Estimate (50+30+20):

Actual:

33 + 46 + 14

Estimate (30+50+10):

Actual:

3Practice

Solve using your favorite strategy.

15 + 20 + 35 =

28 + 12 + 40 =

45 + 8 + 17 =

33 + 27 + 18 =

19 + 41 + 25 =

56 + 14 + 22 =

4Find the Missing Number

Find the missing number.

15 + + 20 = 55

How did you figure it out?

+ 30 + 25 = 75

How did you figure it out?

5Word Problems

Read carefully. Three numbers, one question.

The class read 18 books in September, 22 books in October, and 15 books in November. How many books did the class read in all?

Draw or write your thinking:

books

There were 36 boys at the soccer game, 24 girls, and 20 adults. How many people were at the game?

Draw or write your thinking:

people